Activity of serum cytidine deaminase during pregnancy

A simple and reliable method for the estimation of cytidine deaminase (cytidine aminohydrolase; EC 3.5.4.5) activity in pregnancy serum is described. This enzyme does not require magnesium for activation and is also more stable than deoxycytidylate deaminase (dCMP deaminase, dCMP aminohydrolase; EC 3.5.4.12). There was excellent correlation between the two enzymes (r = 0.92). Both enzymes showed increased activity in abnormal pregnancy. Both enzymes activities were found to be similar in 1305 maternal serum samples and therefore due to the simplicity of cytidine deaminase estimation it is recommended for the screening of large numbers of antenatal sera for abnormal pregnancies.